Safety advocates who want to see rearview cameras in all cars and light trucks to avoid backover deaths have been waiting for a $2.7 billion regulation that the Department of Transportation was required by law to issue a year ago.

It looks like they’ll have to wait a bit longer.

The rule won’t be out this week because the regulatory review isn’t complete, according to a Transportation Department official familiar with the situation who wasn’t authorized to discuss it.

The standard was required to be issued by the end of 2011 under a law signed by President George W. Bush in 2008. The law is named for Cameron Gulbransen, a New York 2-year-old who died after his father accidentally backed over him. When the Transportation Department last delayed the regulation Feb. 28, it issued a statement promising to issue the regulation by the end of the year.

Backup cameras are available now on 57 percent of new cars and 83 percent of light trucks sold in the U.S., according to Edmunds.com.

The rule may save about 146 lives a year, the National Highway Traffic Safety Administration estimated in 2010 when it issued the proposed standard. While the proposed rule didn’t explicitly require rearview cameras, no other technology currently meets the standard.

Backover accidents cause 292 U.S. deaths annually, most frequently killing children and the elderly. Assuming half those deaths can be averted by cameras, the rule would cost about $18.5 million per life saved, according to calculations by the safety agency.